Treasury rose before a government report that economists said will show US housing starts fell in July, signalling residential real estate is failing to contribute to economic growth.
Ten-year yields extended their decline over the past month to more than 60 basis points as signs growth is slowing boosted demand for the safest securities. The MSCI All Country World Index of stocks fell 8 per cent in the same period.
Treasuries gained as reports showed European economic growth slowed more than economists forecast in the second quarter as Germany's recovery almost ground to a halt.
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"Yields will go lower if the data continues to be bad," said Michael Markovic, a senior fixed-income strategist at Credit Suisse Group AG in Zurich.
"We expect Treasury yields to stay low for a while. The market needs to be sure that we are not sliding into a recession before there can be any significant move up."
The benchmark ten-year yield fell three basis points to 2.28 per cent, according to Bloomberg Bond Trader prices. The 2.125 per cent note due August 2021 rose 7/32, or $2.19 per $1,000 face amount, to 98 5/8. Five-year yields also declined three basis points, to 0.96 per cent.
The Federal Reserve took the unprecedented step last week of saying it will keep its benchmark interest rate at almost zero through the middle of 2013 to support the economy.
Ten-year yields slid to a record 2.0346 per cent on August 9. Two-year rates dropped to 0.1568 per cent the same day, also the least ever.
Housing starts dropped 4.6 per cent to a 600,000 annual rate last month, according to the median estimate of economists surveyed by Bloomberg News before yesterday's data.
"We have to get used to the idea that rates are going to stay at historic lows," said Chungkeun Oh, a fixed-income trader in Seoul at Industrial Bank of Korea, South Korea's largest lender to small and medium-sized companies.
"The US economy is still quite bad." Oh said he added to his holdings over the past two weeks.